The KRAS gene encodes a small GTPase transductor protein called KRAS in humans. The protein product performs an essential function of signaling and has major role in cell division in normal tissue. KRAS gene is located on human chromosome 12p12.1. A single amino acid substitution is responsible for an activating mutation with implications in various malignancies, including colorectal carcinoma, ductal carcinoma of the pancreas and mucinous adenoma. The presence of KRAS mutations is directly associated with an absence of response to anti-EGFR monoclonal-antibody-based treatments.